A conventional section bar is described, for example, in German Patent No. 91 03 993. This conventional section bar, which is used as a frame element for the construction of a protective fence, has undercut longitudinal grooves on its sides with a protective screen projecting into the longitudinal groove. In order to secure the protective screen in the longitudinal groove, a wedge-shaped piece is used, which jams the protective screen in the area of the groove opening. The use of an additional wedge results in increased expense in manufacturing such protective fences. Furthermore, due to the fact that the protective screen is connected to the section bar only in the area of the longitudinal groove, a relatively high jamming tension is required to firmly secure the protective screen. In addition, the almost linear jamming of the protective screen in the section groove has the effect that, in the event of a transversal load on the protective screen, this small jammed area acts as a joint, and therefore the protective screen is deformed even under the effect of a moderate load on the entire jammed area.
German Patent No. 39 00 411 describes a section rod which includes grooves and recesses on boundary walls of receptacle grooves, the grooves and recesses functioning to accommodate excess adhesive material, if the walls of a trunk have profiles adhered to them. The peaks of the grooves do not protrude over one of the side walls of the plane formed by the receptacle grooves. The reason for this is that the grooves function to accommodate excess adhesive material, and have no influence on the retention force for the walls of the trunk.
In German Patent No. 43 07 492, a rubber seal having sealing lips for a flat element is shown. The element is inserted together with the flat element into a longitudinal groove. The rubber seal, however, is very soft. Thus, the rubber seal does not influence the retention force for the flat element.
In German Patent No. 42 08 720, a section rod is described which has a receptacle groove having two projections. These have a roughly round shape and are supposed to make possible improved support and two defined points or lines for a retaining element. While the support for the retaining element is good, the retention force for the retaining element is not improved when pulled out.
A profile element described in German Application 20 11 657 is made of an open seam tube of steel having an elliptical cross-section. Slotted edges are bent towards each other and lock in behind the protruding screen elements. Therefore, the external edges of an open seam tube having an elliptical cross-section are bent towards each other. The flat element is then made secure by being locked in.